System for capturing point values for constituting an image with terahertz radiation

Abstract

The device ( 40 ) for capturing point values for constituting an image, comprises: an incoherent source ( 100 ) of rays, the frequency of which is between 0.075 THz and 10 THz for illuminating an object, a sensor ( 415 ) of radiation coming from the object, which comprises an area sensitive to the radiation coming from the source and which emits an electrical signal representative of the intensity of the rays coming from the source and reaching the sensitive area of the sensor, and at least one optical focusing system ( 400, 410 ) with aperture number (F-Number) less than one, situated on the optical path of rays emitted by the source and propagating from the source to the sensor of rays, passing via the object. Preferably, the source ( 100 ) illuminates the object with a sufficiently broad emission spectrum to scan the standing wave in a period shorter than the acquisition time of the sensor. Preferably, the incoherent source has a bandwidth of several GHz, preferably at least equal to 12 GHz at −100 dB.

The invention claimed is: 
     
       1. A device capturing point values for constituting an image of an object, that comprises:
 an incoherent source of rays, the frequency of which is between 0.075 THz and 10 THz for illuminating the object; 
 a sensor of radiation coming from the object, which comprises an area sensitive to the radiation coming from the source and which emits an electrical signal representative of the intensity of the rays coming from the source and reaching the sensitive area of the sensor; and 
 at least one optical focusing system with aperture number, or f-number, that is less than one, situated on the optical path of rays emitted by the source and propagating from the source to the sensor of rays, passing via the object, said at least one optical focusing system comprising at least one lens between the incoherent source and the object, to direct the rays emitted by the source on the object and at least one lens between the object and the radiation sensor, to direct the rays from the object onto the sensitive area of the sensor. 
 
     
     
       2. The device according to  claim 1 , wherein the incoherent source has a bandwidth of several GHz. 
     
     
       3. The device according to  claim 1 , wherein the incoherent source has a bandwidth at least equal to 12 GHz at −100 dB. 
     
     
       4. The device according to  claim 1 , wherein at least one optical system comprises an aspheric optical lens. 
     
     
       5. The device according to  claim 4 , wherein the scattering, as a percentage, for the indices of the materials used for the optical lens, over the frequency ranges of the source, is less than 1%. 
     
     
       6. The device according to  claim 4 , wherein the scattering, as a percentage, for the indices of the materials used for the optical lens, over the frequency ranges of the source, is 0.2% from 100 to 300 GHz. 
     
     
       7. The device according to  claim 4 , wherein the scattering, as a percentage, for the indices of the materials used for the optical lens, over the frequency ranges of the source, is 0.5% from 100 to 700 GHz. 
     
     
       8. The device according to  claim 1 , wherein at least one optical component of an optical system has an anti-reflective treatment comprising microstructures in the form of cones or craters. 
     
     
       9. The device according to  claim 1 , wherein at least one optical system comprises an optical lens and the incoherent source of rays is configured to illuminate the whole of the optical lens closest to said source. 
     
     
       10. The device according to  claim 1 , wherein the emission frequency of the incoherent source of rays is modulated. 
     
     
       11. The device according to  claim 1 , wherein the incoherent source of rays comprises a source of thermal-type noise in an IMPATT diode or resistor. 
     
     
       12. The device according to  claim 1 , which comprises proximity electronics to polarize a nano-transistor comprising the photosensitive area, via a gate voltage close to its swing voltage where the standard operation of the transistor is the most nonlinear. 
     
     
       13. The device according to  claim 12 , wherein the rectified signal coming from the nano-transistor is amplified by forcing an asymmetry of the loads in the nano-transistor channel through the injection of a current into the nano-transistor channel, between the drain and the source and/or by using metalized motifs acting as antennas. 
     
     
       14. The device according to  claim 12 , wherein the rectified signal is a continuous potential difference between the Drain and the Source of the nano-transistor measured in common or differential mode. 
     
     
       15. The device according to  claim 12 , wherein the proximity electronics comprises a compensation circuit to adjust for the offset generated by injecting the current between the drain and the source of the nano-transistor, for example by using a subtractor assembly. 
     
     
       16. The device according to  claim 1 , wherein the photosensitive area is a nano-transistor, and the signal generated by the THz radiation is a continuous potential difference between the Drain and the Source of the nano-transistor measured in common or differential mode. 
     
     
       17. The device according to  claim 16 , which comprises proximity electronics to polarize the nano-transistor via a gate voltage close to its swing voltage where the standard operation of the transistor is the most nonlinear. 
     
     
       18. The device according to  claim 16 , wherein the rectified signal coming from the nano-transistor is amplified by forcing an asymmetry of the loads in the nano-transistor channel through the injection of a current into the transistor channel, between the drain and the source and/or by using metalized motifs acting as antennas. 
     
     
       19. The device according to  claim 1 , which comprises at least one low-drift low-noise amplifier, which amplifies the signal over the dynamics of an analog-digital converter.